Toshiba Q7 Fault Codes List

Troubleshoot your legacy Toshiba Q7 (Flowmate) drive with our updated fault code guide. Learn to interpret OC, OL, and EF trips, view past faults, and reset the drive safely.

Toshiba Q7 Fault Codes Reference Table

Below is the complete list of trip codes and alarms. Please refer to this table to match the code on your display with the specific hardware or parameter issue.

Toshiba Q7 ASD Faults, Alarms, and Trips

Fault Code and Meaning	Cause and Remedy
CM1 Comm1 Error (Internal communications error)	Cause: Improperly programmed ASD. Improper communications settings. Improperly connected cables. Remedy: Check internal communication settings and cabling.
CM2 Comm2 Error (External communications error)	Cause: Improper communications settings. Improperly connected cables. Remedy: Verify external communication device settings and wiring.
EMG Emergency Off	Cause: Stop|Reset pressed twice at the keypad. EOFF command received remotely. Remedy: ASD reset required.
MOFF Main Undervoltage	Cause: Low 3-phase utility voltage. Undervoltage condition at the 3-phase AC input. Remedy: Check input power supply.
OC Over Current	Cause: Defective IGBT (U, V, or W). ASD output phase-to-phase short. The ASD is starting into a spinning motor. Motor/machine jammed. Mechanical brake engaged while the ASD is starting/running. Accel/Decel time is too short. Voltage Boost setting is too high. Load fluctuations. Remedy: ASD output to the motor is connected incorrectly. Disconnect the motor and retry. Check for jammed motor/machine. Adjust Accel/Decel time.
*OH Overheat	Cause: ASD is operating at an elevated temperature. ASD is too close to heat-generating equipment. Cooling fan vent is obstructed. Cooling fan is inoperative. Internal thermistor is disconnected. Remedy: Check clearance and ventilation (see Mounting instructions). Replace cooling fan if inoperative.
OJ Timer (Run-time counter exceeded)	Cause: Run-time counter limit reached. Remedy: Type Reset required; select Clear run timer.
*OLI ASD Overload	Cause: The carrier frequency is too high. An excessive load. Acceleration time is too short. DC damping rate is set too high. The motor is starting into a spinning load after a momentary power failure. The ASD is improperly matched to the application. Remedy: Reduce carrier frequency. Increase acceleration time. Verify ASD sizing for the application.
OLM Motor Overload	Cause: V/f parameter improperly set. Motor is locked. Continuous operation at low speed. The load is in excess of what the motor can deliver. Remedy: Adjust V/f parameters. Check for locked motor.
*OLR Resistor Overload	Cause: Excessive current at the Dynamic Braking Resistor. Deceleration time is too short. DBR configuration improperly set. Remedy: Increase deceleration time. Check DBR settings.
*OP Overvoltage	Cause: ASD attempting to start into a spinning motor after momentary power loss. Incoming utility power is above the specified range. Decel time is too short. DBR resistance value is too high or DBR function turned off. Overvoltage Stall feature is turned off. System is regenerating. Load instability. Remedy: Install inductive filter for voltage spikes. DBR required. Disable the Ridethrough function (F302).
OT Overtorque	Cause: ASD is not correctly matched to the application. Parameter F616 or F617 setting is too low. Obstructed load. Remedy: Adjust torque parameters. Clear load obstruction.
*POFF Control Undervoltage	Cause: Defective Control board. Excessive load on power supply. Low input voltage. Undervoltage condition at the 5, 15, or the 24 VDC supply. Remedy: Check control board and power supply load.
PtSt Reference Point	Cause: Two speed-reference frequency setpoints are too close to each other. Remedy: Increase the difference between the setpoints.
UC Undercurrent	Cause: Output current is below level defined at F611 for time set at F612. Remedy: Check load connection and parameters F611/F612.
Atn Autotune Active	Cause: Indicates that the Autotune function is active. Remedy: Wait for Autotune to complete.
db / dbOn DC Braking Active	Cause: DC Injection function being carried out. dbOn appears when Shaft Stationary function is active. Remedy: Notification only. No action required unless unexpected.
Inverter (ASD) OL Inverter Overload Trip	Cause: Acceleration time is too short. DC Injection current is too high. V/f setting needs to be adjusted. Motor running during restart. ASD or the motor is improperly matched to the application. Remedy: Increase acceleration time. Adjust V/f settings or DC injection parameters.
Autotuning Err Autotuning Error	Cause: Readings significantly inconsistent with configuration. A non-3-phase motor is being used. Incorrect settings at parameter F400, F413, or F414. Using a motor significantly smaller than the ASD rating. ASD output cabling is too small, too long, or has interfering EMF. Motor is running during Autotune. Remedy: Verify motor type and parameter settings. Ensure motor is stopped before Autotuning.
Comm Error Communication Error	Cause: Communication malfunction. Improper or loose connection. Improper system settings. Remedy: Check connections and settings.
Ctrl Undervolts Control Undervoltage	Cause: Undervoltage condition at the 5, 15, or 24 VDC supply. 3-phase input voltage low. Remedy: Check input voltage levels.
CPU Error CPU Malfunction	Cause: CPU malfunction. Remedy: Contact service if power cycle does not resolve.
Main Undervolts Main Undervoltage	Cause: 3-phase input voltage low. Defective control board. Excessive load on the power supply. Undervoltage/Ridethrough settings require adjustment. Remedy: Check mains voltage and power supply load.
Fuse Fuse Open	Cause: Internal DC bus fuse is open. Remedy: Check for short circuits; Replace fuse/ASD.
DBR Overcurrent DBR Overcurrent	Cause: ASD inability to discharge the bus voltage during regeneration. No dynamic braking resistor (DBR) installed. Deceleration time is too short. Improper DBR setup information. Defective IGBT7 (or IGBT7 ckt.). 3-phase input voltage is above specification. Remedy: Install DBR or check DBR setup. Increase deceleration time.
DBR Overload DBR Overload	Cause: Deceleration time is too short. DBR setting adjustment required. Overvoltage Stall setting adjustment required. Remedy: Adjust Decel time and Stall settings.
GND Fault Ground Fault	Cause: Ground fault at the motor. Ground fault at the output of the ASD. Current leakage to Earth Ground. Remedy: Check motor and output wiring for shorts to ground.
Ctrl EEPROM Err Control EEPROM Error	Cause: Internal EEPROM malfunction. Remedy: Contact service.
EEPROM Write Err EEPROM Write Error	Cause: EEPROM write malfunction. Remedy: Retry operation or contact service.
E-Off Emergency Off	Cause: Emergency Off command received via keypad or remotely. Remedy: Reset ASD.
Encoder Loss Encoder Loss	Cause: Encoder signal missing while running during closed-loop operation. Remedy: Check encoder connections.
Flash Error Flash Memory Error	Cause: Flash memory malfunction. Remedy: Contact service.
Gate Array Error Gate Array Error	Cause: Defective Gate Array or Gate Array malfunction. Remedy: Contact service; Board replacement may be required.
In(put) Phase Loss Input Phase Loss	Cause: 3-phase input to the ASD is low or missing. Remedy: Check input power phases.
Load Drooping Load Drooping	Cause: Load requirement is in excess of the capabilities of the motor. Remedy: Reduce load or resize motor.
Load End OC Load End Overcurrent	Cause: Improper wiring at the ASD output to the motor. Remedy: Check output wiring.
Under Curr(ent) Trip Undercurrent Trip	Cause: Improper Low Current detection level setting. Remedy: Adjust detection level settings.
Main EEPROM Err Main EEPROM Error	Cause: Internal EEPROM malfunction. Remedy: Contact service.
Motor Overload Motor Overload	Cause: V/f setting needs to be adjusted. Motor is locked. Continuous operation at low speed. Load requirement exceeds ability of the motor. Startup frequency setting adjustment required. Remedy: Check for locked motor. Adjust V/f and startup parameters.
Option PCB Error Option PCB Error	Cause: Optional device malfunction. Improper system settings (at ASD or optional device). Loose or improper connection. Remedy: Check connections and settings of optional devices.
Out(put) Phase Loss Output Phase Loss	Cause: 3-phase output from the ASD is low or missing. Remedy: Check motor connections and ASD output.
Overcurrent Acc Overcurrent during Accel	Cause: V/f setting needs to be adjusted. Restart from a momentary power outage. The ASD is starting into a rotating motor. ASD/Motor not properly matched. Phase-to-phase short (U, V, or W). Accel time too short. Voltage Boost setting is too high. Motor/machine jammed or brake engaged. ASD current exceeds rated limit (340% or 320% depending on HP) during acceleration. Remedy: Adjust Accel time and Voltage Boost. Check for shorts or mechanical jams.
Overcurrent Dec Overcurrent during Decel	Cause: Phase-to-phase short (U, V, or W). Deceleration time is too short. Motor/machine jammed or brake engaged. ASD current exceeds rated limit (340% or 320%) during deceleration. Remedy: Increase Decel time. Check for shorts or jams.
Overcurrent Run Overcurrent during Run	Cause: Load fluctuations. ASD is operating at an elevated temperature. ASD current exceeds rated limit during fixed-speed run. Remedy: Check load conditions and cooling.
Overheat Overheat	Cause: Cooling fan inoperative. Ventilation openings are obstructed. Internal thermistor is disconnected. Remedy: Clean vents and check fans.
Speed Error Speed Error	Cause: Motor speed is greater than commanded speed (with encoder). Improper encoder connection or setup. Defective encoder. Remedy: Check encoder and setup.
Overtorque Overtorque	Cause: Torque requirement in excess of settings (F616/F617) for time set at F618. ASD improperly matched to application. Load is obstructed. Remedy: Clear obstructions. Adjust torque limits if safe.
Overvolt Accel Overvoltage during Accel	Cause: Motor running during restart. Remedy: Ensure motor is stopped or enable catch-on-fly if available.
Overvolt Decel Overvoltage during Decel	Cause: Deceleration time is too short. DBR value is too high or DBR required. Stall protection is disabled. 3-phase input voltage out of specification. Input reactance required. Remedy: Increase Decel time. Install/Check DBR.
Overvolt Run Overvoltage during Run	Cause: Load fluctuations. 3-Phase input voltage out of specification. Remedy: Check input voltage stability.
Positional Err Positional Error	Cause: Resulting position exceeds limits of Position Control setting. Remedy: Check position control settings and limits.
RAM/ROM Err RAM or ROM Error	Cause: Internal RAM or ROM malfunction. Remedy: Contact service.
Sink/Source Error Sink/Source Configuration Error	Cause: Improperly positioned Sink/Source jumper. Sink/Source configuration of option device is incorrect. Remedy: Check jumper positions and option device configuration.
Type(form) Error Typeform Error	Cause: Firmware information loaded into Gate Driver board is inconsistent with device. Gate Driver board has been replaced or is defective. Remedy: Verify firmware version and board compatibility.
U/V/W Phase OC Phase Overcurrent (U, V, or W)	Cause: Low impedance at the U, V, or W lead of the ASD output. Remedy: Check output cabling and motor insulation for shorts.

 

How to Read Q7 Faults via Keypad

Since the Q7 is a legacy drive, connecting it to modern software can be difficult. In 2026, the on-board keypad (Electronic Operator Interface) is your best tool for diagnostics:

• Current Fault: When the drive trips, the display immediately flashes the fault code. Do not reset the drive until you have noted this code.
• Trip History: The Q7 stores the last 4 trips in its non-volatile memory. Press the MON (Monitor) key and use the arrow keys to scroll to the “Trip Monitor” section (often labeled as tr-1 through tr-4).
• Status at Trip: By selecting a past trip in the monitor menu, you can often view the output frequency and current at the moment of failure. This data is critical for determining if the fault happened during startup (high current) or steady-state operation.

General Troubleshooting Steps

Given the age of Q7 drives in 2026, many faults are related to component aging. Perform these checks:

1. Overcurrent (OC1/OC2/OC3): OC1 is Accel, OC2 is Decel, OC3 is Constant Speed. Check for a shorted motor or ground fault. If the motor tests fine, the drive’s internal IGBT snubber circuits or capacitors may be degraded.
2. Overload (OL1/OL2): OL1 is Motor Overload; OL2 is Drive Overload. Ensure the “Motor Rated Current” parameter matches the motor nameplate. Check for mechanical binding on pumps or clogged filters on fans.
3. Earth Fault (EF): This indicates a current leak to the ground on the output side. Do not reset repeatedly. Disconnect the motor leads and perform a megger test on the motor and cabling immediately.

Frequently Asked Questions (FAQ)

Q: What is the difference between a “C” code and a “Trip”?

A: A flashing C code (like CL for Current Limit or CO for Overcurrent Alarm) is a warning that the drive is actively compensating to prevent a trip. A Trip (like OC1) stops the output completely.

Q: How do I reset a Toshiba Q7 fault?

A: You can reset the drive using one of these methods:

• Press the STOP/RESET key on the keypad.
• Momentarily short the RES (Reset) control terminal to the Common (CC) terminal.
• Cycle the main input power (Turn OFF, wait for the display to go dark, Turn ON).

Q: Why does the drive display “OFF”?

A: OFF is the standard standby status. It means the drive has power but has not received a valid “Run” command (Forward or Reverse) from the terminal strip or keypad.